1. Field of the Invention
The embodiments of the invention generally relate to robot components utilized in high temperature semiconductor processing systems.
2. Background of the Related Art
Semiconductor substrate processing is typically performed by subjecting a substrate to a plurality of sequential processes to create devices, conductors and insulators on the substrate. These processes are generally performed in a process chamber configured to perform a single step of the production process. In order to efficiently complete the entire sequence of processing steps, a number of process chambers are typically coupled to a central transfer chamber that houses a robot to facilitate transfer of the substrate between the surrounding process chambers. A semiconductor processing platform having this configuration is generally known as a cluster tool, examples of which are the families of PRODUCER®, CENTURA® and ENDURA® processing platforms available from Applied Materials, Inc., of Santa Clara, Calif.
Generally, a cluster tool consists of a central transfer chamber having a robot disposed therein. The transfer chamber is generally surrounded by one or more process chambers. The process chambers are generally utilized to process the substrate, for example, performing various processing steps such as etching, physical vapor deposition, ion implantation, lithography and the like. The transfer chamber is sometimes coupled to a factory interface that houses a plurality of removable substrate storage cassettes, each of which houses a plurality of substrates. To facilitate transfer between a vacuum environment of the transfer chamber and a generally ambient environment of the factory interface, a load lock chamber is disposed between the transfer chamber and the factory interface.
As line width and feature sizes of devices formed on the substrate have decreased, the positional accuracy of the substrate in the various chambers surrounding the transfer chamber has become paramount to ensure repetitive device fabrication with low defect rates. Moreover, with the increased amount of devices formed on substrates both due to increased device density and larger substrate diameters, the value of each substrate has greatly increased. Accordingly, damage to the substrate or yield loss due to non-conformity because of substrate misalignment is highly undesirable.
A number of strategies have been employed in order to increase the positional accuracy of substrates throughout the processing system. For example, the interfaces are often equipped with sensors that detect substrate misalignment within the substrate storage cassette. See U.S. patent application Ser. No. 6,413,356 issued Jul. 2, 2002 to Chokshi, et al. Positional calibration of robots has become more sophisticated. See U.S. patent application Ser. No. 6,648,730 issued Nov. 18, 2003 to Chokshi, et al. Additionally, methods have been devised to compensate for substrate misplacement on the blade of the robot. See U.S. Pat. No. 5,980,194, issued Nov. 9, 1499 to Freerks, et al., and U.S. Pat. No. 4,944,650, issued Jul. 31, 1490 to T. Matsumoto. Further methods have been devised to compensate for thermal expansion of the robot linkages. See U.S. Pat. No. 7,039,501, issued May 2, 2006 to Freeman, et al.
However, these strategies for increasing the accuracy of the robot generally do not compensate for thermal expansion for expansion and contraction experienced by the end effector (e.g., blade) robot as heat is transferred to the end effector from hot wafers and from hot surfaces within the process chambers. As evolving process technology has led to higher operating temperatures for many processes, transfer robots are increasingly exposed to high temperatures. Due to the increased thermal exposure of transfer robots, further strategies must be developed to minimize the adverse effect of robotic thermal expansion on substrate placement and undesired thermal exchange between the robot and substrate.
Therefore, there is a need for an improved robotic end effector having low thermal expansion to minimize thermal effects on robot positioning while minimizing thermal exchange between the robot and substrate carried thereon.